EXHIBIT 99.1

                      [PROSPERITY BANCSHARES, INC. LOGO]


PRESS RELEASE                                      FOR MORE INFORMATION CONTACT:

                                                                  David Hollaway
                                                         Chief Financial Officer
PROSPERITY BANCSHARES, INC.(SM)                                     979.543.2200
4295 San Felipe                               davidhollaway@prosperitybanktx.com
Houston, Texas 77027                          ----------------------------------

                                                                     Dan Rollins
                                                           Senior Vice President
                                                                    713.693.9300
                                                 danrollins@prosperitybanktx.com
                                                 -------------------------------

FOR IMMEDIATE RELEASE


                        PROSPERITY BANCSHARES, INC.(SM)
                                   TO ACQUIRE
                           TEXAS GUARANTY BANK, N.A.



HOUSTON, February 22, 2002.  Prosperity Bancshares, Inc.(SM) (Nasdaq: PRSP)
announced today the signing of a definitive agreement with American Bancorp of
Oklahoma, Inc. to acquire its wholly-owned subsidiary, Texas Guaranty Bank,
N.A., for $11.8 million in cash.  The acquisition is expected to close in the
second quarter 2002.  The proposed transaction is subject to certain conditions
and approval by regulators.

Texas Guaranty Bank, N.A. operates three (3) offices in Houston, Texas, all of
which will become full service banking centers of Prosperity Bank when the
acquisition is completed.  On December 31, 2001, Texas Guaranty Bank, N.A.
reported total assets of $82.2 million, total deposits of $62.9 million and
total loans of $59.7 million.

"We are excited about the addition of Texas Guaranty Bank's customers to our
existing customer base.  We also are pleased to add Texas Guaranty's experienced
staff to our team of professional bankers," said David Zalman, President and
Chief Executive Officer of Prosperity Bancshares, Inc. "We are pleased that
Texas Guaranty Bank chose to become our partner in providing the finest bank
service available in the markets we serve."


"The decision to sell our bank after operating as an independent bank and
providing quality banking services to our customers  was not easy," said Frank
Maresca, President and Chief Executive Officer of Texas Guaranty Bank.
"However, we are convinced that joining Prosperity Bank is the right choice for
our customers.  We all look forward to becoming a member of the Prosperity team
and continuing our personal involvement with the customers of our bank."

"Our new customers will continue to enjoy the same type of people to people
banking they have enjoyed with Texas Guaranty Bank," said H. E. (Tim) Timanus,
Jr., President and Chief Operating Officer of  Prosperity Bank.  "We are
committed to providing our entire customer base with quality banking products
and services now and in the future."

Prosperity Bancshares, Inc.(SM), formed in 1983, is a $1.262 billion bank
holding company headquartered in Houston, Texas.  Operating under a community
banking philosophy, Prosperity seeks to develop broad customer relationships
based on service and convenience.  Prosperity offers a variety of traditional
loan and deposit products to its customers, which consist primarily of consumers
and small and medium sized businesses.  In addition to established banking
products, Prosperity offers a complete line of services including: Internet
Banking services at www.prosperitybanktx.com, Trust Services, MasterMoney Debit
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Cards, and 24 hour voice response banking.  The bank currently operates twenty-
nine (29) full service banking locations in fourteen (14) contiguous counties
including the Greater Houston Metropolitan Area.  (Angleton, Bay City, Beeville,
Clear Lake, Cleveland, Cuero, Cypress, East Bernard, Edna, El Campo, Fairfield,
Goliad, Hitchcock, Houston - Bellaire, Houston - Downtown, Houston - Medical
Center, Houston - Post Oak, Houston - River Oaks, Houston - Tanglewood, Houston
- - Waugh Drive, Liberty, Magnolia, Mathis, Needville, Palacios, Sweeny, Victoria,
West Columbia, and Wharton.)

                                     - - -

"SAFE HARBOR" STATEMENT UNDER THE PRIVATE SECURITIES LITIGATION REFORM ACT OF
1995: THE STATEMENTS CONTAINED IN THIS RELEASE WHICH ARE NOT HISTORICAL FACTS
CONTAIN FORWARD-LOOKING INFORMATION WITH RESPECT TO PLANS, PROJECTIONS OR FUTURE
PERFORMANCE OF PROSPERITY BANCSHARES, INC.(SM) AND ITS SUBSIDIARIES.  FORWARD-
LOOKING STATEMENTS, WITHIN THE MEANING OF SECTION 21E OF THE SECURITIES EXCHANGE
ACT OF 1934, MAY HAVE BEEN MADE IN THIS DOCUMENT. PROSPERITY'S RESULTS MAY
DIFFER MATERIALLY FROM THOSE IN THE FORWARD-LOOKING STATEMENTS FOR A VARIETY OF
REASONS, INCLUDING ACTIONS OF COMPETITORS; CHANGES IN LAWS AND REGULATIONS
(INCLUDING CHANGES IN GOVERNMENTAL INTERPRETATIONS OF REGULATIONS AND CHANGES IN
ACCOUNTING STANDARDS); CUSTOMER AND CONSUMER DEMAND, INCLUDING CUSTOMER AND
CONSUMER RESPONSE TO MARKETING; EFFECTIVENESS OF SPENDING, INVESTMENTS OR
PROGRAMS; FLUCTUATIONS IN THE COST AND AVAILABILITY OF SUPPLY CHAIN RESOURCES;
ECONOMIC CONDITIONS, INCLUDING CURRENCY RATE FLUCTUATIONS; AND WEATHER. THESE
FACTORS ARE MORE FULLY DESCRIBED IN PROSPERITY BANCSHARES, INC.'S FILINGS WITH
THE SECURITIES AND EXCHANGE COMMISSION.

COPIES OF PROSPERITY BANCSHARES, INC.'S(SM) SEC FILINGS MAY BE DOWNLOADED FROM
THE INTERNET AT NO CHARGE FROM FREEEDGAR, A REAL-TIME ACCESS TO SEC FILINGS SITE
LOCATED AT WWW.FREEEDGAR.COM.
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